To skip the long history and associated griping, scroll down to the short questions at the bottom
Older spacepak R22 system replaced when heat pump died and change to R410 was recommended. Previous system was working GREAT so went with advice of HVAC company to replace entire system (same company that did original install approx 13 years ago). Old system was 5 ton, don't have any more details (sorry)
Spacepak ESP-4860D with 3/4 hp blower motor at 1725 rpm
Paired to Trane XR12 4twr2060a1000ab outside
28 outlets in house (5.6 per ton)
System is working poorly at best (I say not at all). Freezing over constantly and can't keep house cool even on moderate days (b/c always in defrost mode). After several summers of letting the installer try to tweak the system, I was told today that "there is no way this system will work with only 28 outlets and there is no way it could have ever worked from the first day it was installed."
I was informed that the fan motor is "shot" and as a result it is often starting in reverse direction (so short answer was to get it going in right direction and leave fan switch in 'on' mode). I was told this is the result of not enough outlets and therefore too much back-pressure so not enough air is getting into the house and, therefore, not enough air is being pulled out of the house and across the coil so it is freezing up. And the motor died trying to push air into the house.
I was told I would need a new motor at the very least ($$$ installed for same 3/4 hp motor) and I was told that would be a short term fix and what I really needed was a new spacepak (the current unit has HEAVY rust from the constant freezing) and a new condenser outside b/c the Trane has been overworked. Most importantly, I needed at least 7 additional outlets and 10 would be preferred ($$$$$$ quote for condenser, spacepak and install with additional outlets).
To say the least, I was a bit unhappy.
When I asked how the old system was able to work GREAT with 28 outlets I was told that the new systems are much more efficient and that means less powerful fan/fan motor and as a result the current fan motor can't force the same amount of air into the house. Makes perfect sense (the air is a LOT less noisey - but it was never bothersome before).
My question then (I know, finally): Why can't I just swap the motor on the blower wheel with a larger, more powerful motor? I understand that it must still fit on the motor mount correctly in order to line up the drive shaft with the wheel, but certainly a 1 h/p motor would still fit and maybe even more.
Moreover, why not go with a motor that has multiple speeds so a higher rpm could be used on really hot days when needed, and a lower rpm used when not needed (but still enough to force the air out of my limited 28 outlets)?
Needless to say, I'm looking for another HVAC contractor given that I was never told to increase outlets (still have original install paperwork) and was specifically told it wouldn't be needed and all that was "possibly" needed was an increase of the supply duct, which was listed as an option that we chose to be safe - and now I'm told it could never have worked from the begining.
But its the weekend and so while I'm waiting to find another contractor, I'm just wondering why I can't go with a more powerful motor. FWIW, I notice that on my original spacepak paperwork it shows only a 3/4 hp motor as an option, but the current paperwork online shows a 1 h/p option (sounds like its for me :-).
Also, when I asked about the option of going with a multi-speed motor, I was told there was no way to control it from the thermostat. However, I notice that there is a fan relay on the spacepak (not in use with the current motor) and I know there are plenty of thermostats with fan speed controls.
Enough homeowner whining, the short questions are:
(1) can I install a more powerful motor in my spacepak such that it can push more air through my existing 28 outlets?
(2) if so, can I use a multi-speed motor and control it from the indoor thermostat (with a new thermostat of course)?
Thanks for any advice, and enjoy the weekend!
Last edited by jpsmith1cm; 04-06-2012 at 10:09 PM.
Doubt a higher HP motor will help anything.
Dang - it sounded like such a good idea :-(
Can you explain why the more powerful motor won't help?
The explanation of why the less powerful new motor can't push the air through made sense.
Either way, thanks!
1725 RPM is 1725 RPM weather done by a 3/4, or 1 HP motor. So a 1 HP motor of the same speed won't move any more air. And will burn out from lack of air flow.
Up front disclosure, I've never been a fan of High Velocity systems so please forgive my bias. However, we have on a very rare occasion installed them gotten the results both the homeowner and I expected so there was no unhappiness. That said, at least int he case of Unico, they originally recommended with their R-22 systems, 5-outlets per ton of cooling. That increased to 6-outlets per ton within a relatively short period of time and while I do not recall any specific reason being given, it was primarily aimed a quieting down the noise issue by reducing slightly the velocity. That number has again been increased to a recommendation of 7-outlets per ton.
Unfortunately the science of high velocity and energy conservation seem to be at odds with each other. HV is created by the very opposite of lower energy use, that of variable speed blowers and lower velocity. The HV manufacturers had to obtain waivers from the DOE when the new equipment minimum SEER rating jumped from 10-SEER to 13-SEER a number of years ago. Seems not matter the outdoor unit, the method of creating HV at the indoor unit (restricted airflow) restricted the units to 11.5-SEER as their highest rating. I know not where all that waiver stuff stands now and they could very well be producing in excess of 13-SEER.
All of that means I'm suggesting you do need more airflow and that will likely only be created by increasing the duct system airflow. And good luck with the blower motor. Once again, a variable speed blower motor (or ECM constant torque motor) is used with the desire to use less energy. That lowered energy consumption is ONLY achieved at low airflow (low velocity) in most systems. High velocity (high static) is a recipe for high electrical consumption normaly.
If YOU want change, YOU have to first change.
If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!
You could add some insulation to your home and go wit ha 4 ton unit that will actually deliver about 4 tons all the time. Right now you're probably getting barely 4 tons since it's frozen part of the time.
Few years back had the same thing happen. removed old unit put new one in. spac pak and new condenser. unit would frez up all the time. after working on this and could not get it working right. I called spac pak to find out the main trunk line had to be bigger and had to add more outlets. you have to check static in the main run before and after the unit. get that in line and your unit will work as the old one did.
what I have found out most company only put in a few units or only work on a few so its hard to be good with them. have them call spac pak and get all the info needed to fix it.
Sorry for the absence, I've been busy lining up contractors (or at least trying).
BeenThere: Understood completely, I should have added that I was thinking higher rpm along with the higher hp. Don't know that this is even possible given it has to fit in the same location to line up correctly with the blower wheel, but I was just thinking aloud regarding the theory of getting more flow through the same number of outlets.
SkippedOver: I spoke with SpacePak engineer (only two calls - very helpful group given that I'm a homeowner working through a contractor), who said the spec of 5 outlets per ton (which shows on the original manual that came with my current unit) was increased to 7 outlets in order to accomodate the lower rpm motor and he suggested it was more a goal of quiter operation than reduced power consumption (but I didn't get a clear answer on that point and he didn't know the rpm of the previous motor as I didn't know the exact model). He also informed me that if I get a new motor for the unit it would be a 1hp as they no longer offer the 3/4hp - no clear explanation as to why, but he did note that the rpm is still 1725. I couldn't get an answer on whether a motor with higher rpm/hp would solve my problem, but mostly b/c he could only say they didn't offer such an option and that if I found anything elsewhere that would fit corretly, it would decrease the efficiency of the system resulting in higher cost of operation. I tried to stress that at this point I was willing to accept the lower efficiency, but he never got past that issue. All the same, I'm still very happy with the SpacePak assistance.
MotoGuy: If I understand your suggestion, I would need to have the outside unit replaced with a 4 ton unit and keep the current 4860 unit inside (it is rated for use with either a 4 or 5 ton system). Wouldn't I still need to resolve the static pressure problem in order to get the system balanced so that enough air was being pushed into the house in order for enough air to be pulled back through the return and across the coil? I'm not an HVAC engineer, so my apologies for any confusion on my part (but I really do appreciate the effort to educate me).
GregHVACGuy: You are clearly correct, for the current system to work as installed I would need more outlets and a bigger trunk thank before. The supply or trunk line was changed from 7" to 9" with the installation of the current system, but no more outlets were installed (or suggested). I don't have a manometer to check pressure, and it certainly isn't worth buying one - I'm happy to pay a pro for the service (oddly, the two contractors who have visited regarding this problem haven't checked static pressure beyond putting thier hand to the outlets and at the main return checking to see if a piece of toilet paper would be held in place ???).
We have gone in quoting same size and informing customers of the need to increase # of outlets. We just lose the job to someone who tells the customer that is unneeded. Don't know how things came out with the exception of 1 guy who came back to us after someone else put the thing in. I'm with skipped, not a big fan of the stuff either but when done right, we have quite a few (replacement, not duct systems we put in) that work just fine.
They are saying motor failed because it started backwards? Sounds fishy to me there.
Has SpackPak suggested a local dealer well versed in their system that could give you advice after seeing the job?
SpacePak gave me names of two local contractors (only two in my area).
One was contractor that did original install and current install (and all maintenance in between). That is the same contractor that said no add'l outlets needed but now says no way system could have ever worked and only permanent option is to replace entire system (inside and outside units) and add outlets
Other contractor will be here to look at system on Friday.
We did get a second bid when the current system was installed from a Unico dealer that had previously worked with SpacePak systems. Their bid was cheaper, but we chose to stay with the original contractor b/c they did the first install and all maintenance so they knew us and our house. Didn't work out so well and after suffering through 3 summers I think I've been generous and loyal enough (esp given their recent stance that the system is unworkable).
Regarding the motor, when the system was turned on recently there was virtually no air coming out (though it was cold). On the repair visit, the tech said the motor was going in the wrong direction so the fan blade was in the wrong direction and hence the very low air flow. He got it going in the right direction and said to leave it on or risk it starting wrong again (we didn't leave it on, it did start wrong, another repair trip - enough said :-).
When I asked what was causing it to start wrong direction, I was told the motor was shot and that was a common result of the motor dying. When I asked why it was shot I got the fuller answer about trying to push more air with too much back pressure . . . .. . . . get a new system.
Again, many thanks!
A smaller capacity unit will need less airflow. IF you have resrictive supply branches, it might only be able to deliver maybe 1300CFM now when a 5 ton in a spacepack needs around 1800CFM. If the airflow is so low that it's freezing hte coil, then 2 things are happening, the delivered total capacity will be low and you lose overall capacity from the periods where it's shutdown on safety interlocks (low pressure switch).
Originally Posted by miescha
The point being, that there's no point in putting in a 5 ton system if you can't deliver adequate airflow to support it. Sort of like having a car that can go 200mph but putting cheap tires only rated for 105mph. If you're not going to change the tires, you might as well opt for a smaller engine.
Well, the second of two contractors in my area that were recommended by SpacePak stopped by today. The owner of the company came, and brought along a second gentleman whom the owner said was the most qualified in SpacePak installations (I later learned he also has experience with Unico systems).
The pair spent about an hour at the house and charged me $$$ which I thought was MORE than fair for the time of two people and the very knowledgeable advice they offered.
In short, I was told the system as it stands is not dead and in need of replacement - though they acknowledged it was certainly in rougher shape than they would expect of such a new system.
The fan motor in the spacepak needs new bearings and a new capacitor - they gave me the name of a local motor repair shop if I wanted to remove and replace it myself or they could do it for an hourly charge - and they warned me it was a PIA to remove and replace *correctly*
As for the bigger problem of air flow,
(1) they thought the trunk met minimum size requirements, but they noted the first 90 bend was way too close to the spacepak (12") even though there is room for more. They recommended re-working the trunk so that the first bend was between 22-26" from the spacepak.
(2) the first room that gets air from the trunk (connected closest to the unit) is always cold in the summer and REALLY loud air flow - they recommended balancing orifices, but noted that it would likely increase pressure in the trunk and not necessarily result in more airflow via the other outlets.
(3) once the blower motor is replaced/repaired, they felt 3/4 hp at 1725 rpm will not be ablet to 'push' enough air through the current outlets and recommended (wait for it) 7 more outlets min (though they agreed there is no way even remotely easy to get those add'l outlets).
(4) on the question of replacing the fan motor with a larger/different motor, they felt the current system (number of outlets) would work if the motor were able to push more air through the outlets/trunk/etc.... and the field guy that came along with the owner vaguely recalled that the older Unico / SpacePak units had a motor turning at approx 3600 rpm and both felt that a motor of 1 or 1.5 hp at approx 3600 rpm would likely work to move enough air through the system (out and back in).
HOWEVER, they noted that the blower motor is proprietary to spacepak and that while they could find a 1 or 1.5 hp motor with approx 3600 rpm at single phase 208/230 and with a 5/8 spindle and access key, they had never seen another motor with a 7.5" spindle length (its a long reach from the motor to the blower wheel).
Of course, they are willing to try it provided I foot the bill.
My thinking (before getting advice here) is that I will have them re-work the trunk lines for sure, get the current motor rebuilt (make a nice spare if nothing else) and then try the larger/more powerful motor with higher rpm and NOT yet try to find a way to add more outlets.
BUT, I'm fully aware that if the different motor doesn't work out, we will be adding outlets
FWIW: the house is a very old historically significant home with no exterior framing - only 3-ft thick limestone with roof joists sitting on top - getting the additional lines from the garage attic through the limestone is the most difficult part, and the few places lines can be run inside (if you can get there) are already in use. Hard to picture when not here in person, but you get the idea.
But for the difficulty of getting any more outlets in the house, I would add more without hesitation and skip the whole crap with the larger motor that MIGHT work and might not (and keep the less noisey outlets) - but it is worth an initial try.
As always, I'd love to hear your thoughts.
Last edited by jpsmith1cm; 04-13-2012 at 09:41 PM.